@ion berkley
While long endurance solar cell powered flights in the stratosphere by Helios
NASA - Helios and Zephyr
Zephyr ? unmanned aircraft system UAS type aircraft are demonstrably feasible - although not validated by extended flight. There are also any number of UAS that are battery powered both commercial and toys. The implications from the media releases that in a few years South West and Easyjet can be expected to be flying pax on all electric aircraft is completely false. Solar impulse like Gossamer Albatross only shows that there may be niche uses. The amount of energy for powered flight has not altered so the energy density has to be sufficient. Currently there is no battery or electrical generation system that provides anything close to hydrocarbon fuel energy densities which exceed battery capabilities by several orders of magnitude.